The contribution of vascular pathology towards cognitive impairment in older

individuals with intermediate Braak stage tau pathology

Andrew C Robinson1, Federico Roncaroli1,2, Stephen Chew-Graham1, Yvonne S Davidson1,

James Minshull1, Michael A Horan1, Antony Payton3, Neil Pendleton1*, David MA Mann1*

1 Division of Neuroscience & Experimental Psychology, Faculty of Biology, Medicine and

Health, School of Biological Sciences, The University of Manchester, Salford Royal

Hospital, Salford, M6 8HD, UK.

2 Manchester Academic Health Science Centre (MAHSC), Manchester, UK

3 Division of Informatics, Imaging & Data Sciences, Faculty of Biology, Medicine and

Health, School of Health Sciences, The University of Manchester, Oxford Road, Manchester,

M13 9PL, UK.

* These authors contributed equally to the study.

Running title – VCING and cognition at intermediate Braak stages.

Correspondence to: Dr Andrew Robinson, address as above

Email: andrew.c.robinson@manchester.ac.uk; Tel. +44 (0) 161-206-2580.

1

Abstract

Background

The pathological features of Alzheimer’s disease (AD) are well described but little is known

as to how both neurodegeneration and vascular changes might interact in causing cognitive

impairment.

Objective

The present study aims to investigate relationships between vascular and AD pathology in

cognitively healthy and cognitively impaired individuals with a particular emphasis on those

at intermediate Braak tau stages.

Methods

We investigated the interplay between Braak tau stage and measures of vascular pathology as

described by the vascular cognitive impairment neuropathology guidelines (VCING) in 185

brains from the Brains for Dementia Research programme and The University of Manchester

Longitudinal Study of Cognition in Healthy Old Age. VCING asserts that at least one large

(>10mm) infarct, moderate/severe occipital leptomeningeal cerebral amyloid angiopathy and

moderate/severe arteriosclerosis in occipital white matter accurately predicts the contribution

of cerebrovascular pathology to cognitive impairment.

Results

We found that the extent of arteriosclerosis in the occipital white matter did not differ

between cognitive groups at intermediate (III-IV) Braak stages whereas moderate/severe

leptomeningeal occipital cerebral amyloid angiopathy was greater in cognitively impaired

than normal individuals at Braak stage III-IV. This finding remained significant after

controlling for effects of age, sex, CERAD score, Thal phase, presence/severity of primary

age-related tauopathy, presence/severity of limbic-predominant age-related TDP43

encephalopathy and small vessel disease in basal ganglia.

Conclusion

Interventions targeting cerebral amyloid angiopathy may contribute to delay the onset of

cognitive impairment in individuals with intermediate Alzheimer’s type pathology.

Keywords: Alzheimer’s disease, cerebral amyloid angiopathy, cognition, dementia,

neuropathology.

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Introduction

The relationships between cognitive trajectories and pathological features are ideally

explored in longitudinal studies, which have brain donation and post-mortem brain

examination as an end point [1-13]. In a recent study based on The University of Manchester

Longitudinal Study of Cognition in Healthy Old Age (UMLCHA), no clear single

pathological cause of cognitive impairment could be determined for 10% of cognitively

impaired individuals [11]. In these cases, low loads of misfolded tau, amyloid-β (Aβ), alpha

synuclein and pathological changes in brain vessels may have combined to cause cognitive

impairment. Other longitudinal studies on aged individuals have had similar findings [2, 12,

14, 15] indicating a need to explore the synergistic contribution of vascular co-morbidity.

Braak staging [16] measures the progression of misfolded tau accumulation where higher

stages denote more advanced Alzheimer’s disease (AD) pathology. Previous studies [17]

have suggested that Braak stage III is an important point of transition in the progression of

AD. It is of note that some individuals at this Braak stage display cognitive impairment

whereas others do not. Various factors have been examined to understand this discrepancy,

including insulin resistance [18] and oxidative stress [19], but the full impact of vascular

pathology on the cognitive status of individuals at intermediate Braak stages remains to be

thoroughly investigated.

Attempts have previously been made to elucidate the relationships between Braak stage,

cerebral amyloid angiopathy (CAA) and cognitive impairment. A recent study based on the

Religious Orders Study cohort [20], observed that individuals with CAA were more likely to

be at Braak stage III than those without CAA. These individuals were also more likely to

score lower on test of global cognition and memory suggesting that CAA has an effect on

cognition in individuals at Braak stage III.

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A multicentre study [21] (Vascular Cognitive Impairment Neuropathology Guidelines

(VCING)) aimed to elucidate which of the various vascular pathologies best predicted

cognitive impairment. The authors found that at least one large (>10mm) infarct,

moderate/severe occipital leptomeningeal CAA and moderate/severe arteriosclerosis in

occipital white matter (WM) could accurately predict the contribution of cerebrovascular

pathology to cognitive impairment. Thus, VCING measures can act as surrogate markers for

extent of vascular cognitive impairment and also for the extent of CAA or SVD within the

brain as a whole. VCING criteria established the main pathological changes in vessels that

are responsible for cognitive impairment. However the study did not take into account the

impact of co-existent pathologies on the cognitive status.

In this study we have investigated the interplay between tau-related pathology, as measured

by Braak stage, and the changes in vascular pathology according to VCING criteria, in both

cognitively normal and cognitively impaired individuals recruited in the Manchester arm of

the Brains for Dementia Research (BDR) programme and UMLCHA study. We focussed

principally on those individuals with AD pathology (without concomitant or secondary

pathologies) and those with ageing-related pathology only. We also focussed on cases

showing a mismatch between clinical phenotype and the extent of AD features at post-

mortem examination. We hypothesised that vascular changes as measured by VCING may

drive dementia in those individuals where AD pathology alone would not explain their

cognitive impairment. We found that concomitant occipital leptomeningeal CAA, rather than

coincidental arteriosclerosis in the occipital WM, could explain why some individuals with

intermediate levels of tau pathology were cognitively impaired while others with the same tau

load were cognitively normal.

Material and Methods

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The present study combines the UMLCHA and the Manchester arm of the BDR cohorts.

Details concerning clinical characteristics and neuropathological features of these cohorts

have been presented by the authors elsewhere [10-12].

For the UMLCHA, cognitive status at death was assigned using a combination of last

modified Telephone Instrument for Cognitive Status (TICSm) score (cut off point of 21),

patient notes obtained via the participants’ general practitioner, cause of death as recorded on

the death certificate and information gained from the Brain Bank Coordinator (SCG). Using

cognitive status at death and neuropathological findings, diagnostic accuracy was

approximately 74% within the ULMCHA. For the BDR, participants underwent cognitive

assessments either via telephone interview (for those individuals without memory problems,

participants without a significant hearing impairment, study partners for control participants,

for follow up and retrospective interviews of control participants), or via a visit to the

participant’s home (for the initial control visit, people with an existing diagnosis of dementia

and controls with a significant hearing problem). Cognitive status was assigned using the

Clinical Dementia Rating with a cut-off point of 0.5. Details of cognitive assessments have

been previously described [12]. Using cognitive status at death and neuropathological

findings, diagnostic accuracy was approximately 71% within the BDR cohort.

Neuropathological Assessment

One hemi-brain was fixed in 10% neutral buffered formalin for 3-4 weeks; the other hemi-

brain was frozen at -80oC. Standard blocks of frontal (mid frontal and superior frontal gyri),

cingulate, temporal (including superior and middle temporal gyrus), inferior parietal and

occipital cortex, entorhinal cortex and hippocampus, amygdala, corpus striatum (caudate

nucleus, putamen and globus pallidus), thalamus, midbrain (to include substantia nigra, III

cranial nerve nucleus and red nucleus), brainstem (to include locus coeruleus and dorsal vagal

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nucleus) and cerebellum with the dentate nucleus were cut from the fixed tissue and

processed into wax blocks. One section was stained with haematoxylin-eosin and further

sections (6µm) were immunostained for Aβ (Cambridge Bioscience, monoclonal antibody

4G8, 1:3000), tau proteins phosphorylated at Ser202 and Thr205 (P-tau) (Innogenetics,

monoclonal antibody AT8, 1:750), phosphorylated α-synuclein (rabbit polyclonal antibody

#1175, 1:1000) (kind gift of Dr Masato Hasegawa at Tokyo Metropolitan Institute of Medical

Science, Japan) and phosphorylated and non-phosphorylated TDP-43 (polyclonal antibody,

10782-2-AP, Proteintech, Manchester, 1:1000). For antigen retrieval, sections were either

immersed in 70% formic acid for 20 minutes (for Aβ) or (for the other antibodies) treated in

microwave oven or pressure cooker (for 30 minutes, reaching 120 degrees Celsius and >15

kPa pressure) in 0.1M citrate buffer, pH 6.0, prior to incubation with primary antibody.

Vascular pathologies were assessed following the VCING criteria [21] including the presence

or absence of i) one or more large (>10mm) cerebral infarcts; ii) moderate or severe occipital

leptomeningeal CAA (Figure 1); iii) moderate or severe occipital WM arteriosclerosis. As

well as the binary scores for individual VCING measures, an overall VCING likelihood

(Low, Moderate or High) that cerebral vascular disease contributed to cognitive impairment

was attributed to each case. In addition, small vessel disease (SVD) in basal ganglia (BG)

was also semi-quantitatively assessed (0 – None; 1 – Mild; 2 – Moderate; 3 – Severe).

Cohen's κ was conducted on a random subset of cases (n=40) to determine inter-rater

reliability of semi-quantitative scores for SVD in BG. There was moderate agreement

between the scores of the two neuropathologists (κ = 0.510, p < 0.001).

By analysing the immunostained sections, we were able use consensus criteria to establish the

presence and staging of neurodegenerative diseases such as AD [22], DLB/Parkinson’s

disease [23-25], Fronto-temporal lobar degeneration (FTLD) [26, 27], Corticobasal

degeneration (CBD) [28], Progressive supranuclear palsy (PSP) [29], Multiple system

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atrophy (MSA) [30], Argyrophilic grain disease (AGD) [31], Primary ageing-related

tauopathy (PART) [32], Age Related Tau Astrogliopathy (ARTAG) [33] and Limbic-

predominant age-related TDP-43 encephalopathy (LATE) [34].

For the purpose of this study, we excluded all cases where the primary neuropathological

diagnosis was not AD (DLB/PD = 42; AGD = 4; CBD = 4; PSP = 3; FLTD = 3; MSA = 1;

No available diagnosis = 2) and also excluded AD cases where there was any concomitant or

secondary pathology (other than CAA or SVD; n = 45). We included cases of PART and

LATE due to the fact that they are common ageing-related conditions. However, to avoid

skewing results, we ensured that the presence and staging of PART and LATE pathologies

was included in regression analyses. Although all brain regions were used in

neuropathological diagnosis to enable the inclusion of relevant cases, brain regions relevant

to Braak staging and VCING were the main focus of the present study.

The two ongoing cohorts currently comprise 289 subjects. After applying the above exclusion

criteria, a total of 185 participants (87 BDR and 98 UMLCHA) were considered eligible for

the present study (Supplementary table 1).

Neuropathological diagnoses were assigned by experienced neuropathologists (DM & FR).

Genetic analysis

DNA was extracted from frozen brain tissue using REDExtract-N-Amp™ Tissue PCR Kit

(Sigma) or from previously obtained blood samples (3 cases from UMLCHA). The APOE

genotype was determined using routine polymerase chain reaction (PCR) methods [35].

APOE genotype could not be determined for 2 UMLCHA and 5 BDR participants due to lack

of frozen brain tissue or blood samples.

Statistical analysis

7

Pearson’s Chi-squared test was used to compare demographic features and to analyse whether

there were differences in vascular markers (as measure by VCING) between the various

Braak stage groups. Fisher’s Exact test was used when the expected count was less than five.

Logistic regression was used to investigate whether adjustment for sex, age at death, presence

of APOE ε4 allele(s), CERAD score [36], Thal phase [37], PART [32], LATE-NC [34] and

SVD in BG made any difference to significant outcomes when analysing VCING measures

between cognitive status groups.

A p value of < 0.05 was considered significant for all tests.

Results

Demographics

The demographics of eligible participants, split by cohort, are shown in Table 1. Of the 185

eligible participants, 111 (60%) were female. 86 of the eligible participants (47%) had

cognitive impairment/dementia whereas 99 (53%) remained cognitively unimpaired. Of the

182 participants who were genotyped for APOE, 66 (36%) carried one or more APOE ε4

allele(s). The mean age at death of eligible participants was 84.9±9.7 (BDR 80.5±11.2;

UMLCHA 88.8±5.8).

In order to investigate the impact of VCING pathology in participants with cognitive

impairment where tau-related pathology was insufficient to meet criteria for AD, scores for

vascular pathology for both cognitively impaired and cognitively normal eligible participants

in the BDR and the UMLCHA cohorts were compared according to Braak stage grouped into

0-II, III-IV and V-VI. To do this, we assessed the brain regions specified in Braak staging

and in VCING criteria.

Braak tau stage and VCING

8

Braak tau stage and VCING of eligible participants, split by cohort and cognitive status, are

shown in Table 2. Of the 185 eligible participants, 99 were considered cognitively

unimpaired and 86 were considered cognitively impaired. Of those considered cognitively

unimpaired, 82 were Braak stage 0-II and 17 were Braak stage III-IV. Of those considered

cognitively impaired, 13 were Braak stage 0-II, 36 were Braak stage III-IV and 37 were

Braak stage V-VI. The majority (77.9%) of cognitively impaired individuals were considered

to have a low likelihood that cerebral vascular disease contributed to cognitive impairment

according to the VCING criteria.

Comparisons of vascular pathology between Braak stage groups

Initially, comparisons between Braak stage groups and VCING measures were made

irrespective of the presence or absence of cognitive impairment. This analysis showed

significant increases in the level of leptomeningeal CAA in the occipital lobe between Braak

tau stages 0-II, and stages III-IV (p<0.001) and also stages V-VI (p<0.001), but not between

stages III-IV and V-VI (p=0.970) (Figure 2A).Finally, there were significant differences

found for total VCING scores between stages 0-II and stages III-IV (p=0.024) (Figure 2B).

No differences between Braak stage groups were observed for presence of infarction or

moderate/severe occipital WM arteriosclerosis.

Comparisons of vascular pathology between cognitively normal and cognitively impaired

individuals at each Braak tau stage.

The whole cohort of 185 participants was then stratified into cognitively impaired (n=86) and

cognitively normal (n=99) subgroups. When comparing cognitively impaired and cognitively

normal individuals at Braak stage 0-II, no significant differences were found for infarctions

(p=0.720) (Figure 3A), moderate to severe occipital CAA (p=0.149) (Figure 3B), moderate to

severe occipital WM arteriosclerosis (p=0.062) (Figure 3C) or total VCING scores (p=0.896)

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(Figure 3D). When comparing cognitively impaired and cognitively normal individuals at

Braak stages III-IV, moderate to severe occipital CAA was significantly increased in the

cognitively impaired subgroup when compared with the cognitively unimpaired subgroup

(p=0.049) (Figure 3B). There were no such differences for infarcts (p=0.642) (Figure 3A),

moderate to severe occipital WM arteriosclerosis (p=0.447) (Figure 3C) or total VCING

scores (p=0.933) (Figure 3D). As there were no cognitively normal individuals at Braak

stages V-VI, comparisons between the cognitive groups could not be made.

Comparisons between Braak stage III and Braak stage IV

There were no significant differences in age at death, sex, or cognitive impairment between

individuals at Braak stage III and Braak stage IV. Likewise, there were no significant

differences in any of the vascular measures assessed between individuals at Braak stage III

and Braak stage IV.

Regression analyses

Regression analysis showed that sex, age at death, presence of APOE ε4 allele(s), CERAD

score, Thal phase, PART, LATE-NC and SVD in BG had no effect on the outcome of

significant results found for moderate to severe occipital CAA at Braak stages III-IV between

cognitively impaired and cognitively normal individuals (OR=4.379; p=0.049) (Table 3).

Discussion

A correlation with dementia can only be established in brains of those individuals with

extensive accumulation of misfolded tau in the neocortex (higher than Braak stage IV).

Conversely, intermediate Braak stages (III – IV) can be seen in either cognitively impaired or

cognitively normal subjects. Consequently, we tested for associations between the extent of

tau, measured by Braak stage, and vascular pathology, measured by VCING, to assess the

impact of vascular changes in cognitively impaired individuals at Braak stages III-IV. Owing

10

to the differences in cognitive testing between BDR and UMLCHA cohorts, it was not

possible to use an individual test score to set a threshold for cognitive impairment. However,

the final decision of whether an individual had been cognitively impaired in life came from

clinicians heavily involved in each study. Thus, a high clinical/neuropathological diagnostic

concordance was achieved in each of the cohorts.

In the present study, moderate/severe occipital leptomeningeal CAA in the occipital lobe was

the most important finding with regard to potential associations between Braak tau stages and

measures of vascular pathology in cognitively impaired and normal individuals. Occipital

leptomeningeal CAA was more severe in the cognitively impaired than in cognitively healthy

individuals who were at Braak tau stages III-IV, a finding which is supported by a recent

work on participants in the Religious Orders Study [20]. Most importantly, this correlation

remained valid after controlling for the effects of age at death, sex, presence of APOE ε4

allele(s), CERAD score, Thal phase, presence/severity of PART pathology, presence/severity

of LATE pathology and SVD in BG indicating that it is specifically CAA and not overall Aβ

pathology (or PART/LATE pathology) that is contributing to cognitive status in individuals

at Braak tau stages III-IV. It is worthy of note that there were no demographic or VCING

differences between individuals at Braak stage III and Braak stage IV.

As expected, the degree of occipital leptomeningeal CAA was greater at Braak stages III-IV

and Braak stages V-VI than in Braak stages 0-II. The extent of occipital leptomeningeal CAA

in cognitively impaired individuals at Braak stages III-IV was significantly greater than that

in cognitively normal individuals at that same Braak stage.

Why CAA found in the posterior part of the brain contributes to the largely frontal/temporal

manifestations of cognitive impairment is unclear. It has been previously shown that CAA-

induced tau phosphorylation can lead to tau-associated neurotoxicity [38]. Thus, there could

be increased levels of tau-associated neurotoxicity in those individuals with CAA at Braak

11

stages III-IV, which may render them more likely to be cognitively impaired. Also, in the

present study, we analysed only occipital leptomeningeal CAA as this was deemed to be the

most clinically relevant. However, the accepted VCING model, which used the three criteria

described in the present study, was the most accurate when analysing the impact of vascular

pathology on cognition. Therefore, moderate to severe occipital leptomeningeal CAA may

act as a ‘surrogate’ marker for CAA in the brain as a whole.

The lack of significant contribution of moderate/severe occipital WM arteriosclerosis to the

generation of cognitive impairment in those individuals with intermediate Braak tau stages

may reflect the overall paucity of extensive occipital WM arteriosclerosis among the

participants whether or not they were cognitively impaired. Indeed, only 28.6% of the

participants exhibited moderate to severe occipital WM arteriosclerosis (26.3% of cognitively

normal individuals and 31.4% of cognitively impaired individuals). It is worthy of note that

most participants who suffered from hypertension within the BDR cohort had been treated

with anti-hypertensive medication, thereby militating against the development of

arteriosclerotic changes in cerebral blood vessels and resulting in the surprisingly low

prevalence of moderate to severe occipital WM arteriosclerosis among the participants

irrespective of cognitive status. The same details on anti-hypertensive therapy available for

individuals within BDR cohort was not available for most individuals within UMLCHA

cohort. However, we can infer that similar protective effects would have occurred in

UMLCHA individuals as they would have been treated in a similar way. The evidence in the

literature of fewer WM hyperintensities on MRI in individuals treated with anti-hypertensive

drugs compared to those not treated [39, 40] supports this suggestion. Ageing-related

changes, including SVD, do not necessarily contribute to the progression or drive an

intermediate, non-clinical Alzheimer-type pathology towards established Alzheimer’s disease

with clinical dementia.

12

The underlying cause of CAA still remains uncertain. It has been suggested [41-44] that the

lack of pulsation in cerebral blood vessels affected by arteriosclerosis may facilitate the

development of CAA by restricting the efflux of extracellular fluid containing Aβ peptides,

especially Aβ40, from the brain thereby promoting their aggregation and deposition within the

wall of small arteries and arterioles. On face value, our study might argue against this

hypothesis as although there were clear significant differences in CAA between Braak stages

and between cognitively impaired and unimpaired individuals at Braak stages III-IV, there

were no such significant findings regarding moderate/severe occipital WM arteriosclerosis

between cognitively impaired and cognitively normal individuals at any Braak stage.

Although moderate/severe occipital WM arteriosclerosis is only one measure of SVD and it

does not provide an overall picture of severity of SVD, it was previously shown to associate

with cognitive impairment [21]. In addition, the effect of SVD in BG did not alter the

significant findings regarding CAA and cognition at intermediate Braak stages.

This study has some general limitations. As mentioned previously, clinical diagnosis was not

entirely uniform due to the amalgamation of two separate studies into one cohort. However,

the use of patient notes, cause of death, cognitive assessment and clinical team records

allowed the final cognitive diagnosis to be robust for both cohorts. There is always a chance

that recruitment strategies can introduce bias. For example, it could be said that the

geographical areas covered by BDR (North of England) and UMLCHA (Greater Manchester

and Newcastle) may not reflect society as a whole. This could be addressed by future studies

by adopting different strategies and, perhaps, recruiting individuals from a wider

geographical area. During the conception stage, VCING criteria assessed the impact of many

common vascular pathologies before concluding which were most relevant to cognition [21].

However, there is the possibility that vascular pathologies which fall outside the remit of

VCING criteria (for example small/lacunar infarctions or CAA in regions other than the

13

occipital lobe) may interact with one another resulting in a change in cognition. Though this

is outside the remit of the present study, any such interactions could be studied in future

projects. However, it is important to note that VCING is the current consensus criteria and

clearly outlines which vascular pathologies have the greatest effect on cognition. Finally,

Braak staging is based on tau pathology as seen in AT8 immunostain. There is no clear proof

that accumulations of amorphous, unaggregated tau in neurons renders them totally incapable

of neurotransmission, though their functions may be limited. It is possible that cognitively

normal individuals at Braak stage III-IV may actually have very few bona fide tangle-bearing

cells. On the other hand, cognitively impaired people at Braak stage III-IV may have plenty

of tangles which could help to explain the cognitive deficit. Future studies could address this

by using a silver-based staining method, specific for neurofibrillary tangles, and comparing

tangle load between cognitively normal and cognitively impaired individuals at Braak stage

III-IV.

Strengths of the study include the use VCING as up-to-date consensus criteria to assess the

contribution of cerebrovascular pathology to cognitive impairment. This surpasses previous

similar studies which only looked at one measure of vascular pathology in isolation [20]. In

addition, there was robust, uniform neuropathological assessment which allowed the two

different cohorts to be merged into one larger study set for the present study.

In conclusion, the assessment of VCING criteria showed that moderate to severe occipital

leptomeningeal CAA was an important determinant of cognitive status whilst the other

VCING measures were less relevant. Thus, the presence and severity of occipital CAA might

explain why some individuals with intermediate Alzheimer-type pathology are cognitively

impaired and others remain cognitively normal. This effect appeared to be independent of

moderate/severe occipital WM arteriosclerosis, which was equally common amongst

cognitively impaired and cognitively normal individuals with intermediate Alzheimer-type

14

pathology. It is difficult to comment on the mechanisms which link intermediate tau

pathology and CAA-related pathology. Nonetheless we can speculate that age-related

reduction in ‘cerebral reserve’ such as neuroinflammation and synaptic damage could

combine to tip the balance towards cognitive impairment. Our study suggests that

interventions to reduce CAA-related pathology may impact on cognitive impairment in those

individuals with intermediate misfolded tau load.

Acknowledgments/Funding

Longitudinal Cognitive studies were funded by Medical Research Council, Economic and

Social Research Council, The Wellcome Trust (grant reference number 003889) and Unilever

PLC.

The work of Manchester Brain Bank is supported by Alzheimer’s Research UK and

Alzheimer’s Society through the Brains for Dementia Research (BDR) Programme.

We also thank Daniel du Plessis and Piyali Pal for their help and assistance with

neuropathology.

Authors’ contributions

DM and AR devised and designed the study and wrote the paper. AR performed all statistical

analysis.

DM and FR finalised neuropathological diagnosis. FR assisted with preparation of the

manuscript.

JM assisted with the analysis of results and the preparation of the manuscript.

NP finalised clinical cognitive impairment diagnosis and assisted with preparation of the

manuscript.

15

MH helped to finalise clinical cognitive impairment diagnosis and provided clinical data for

UMLCHA cohort.

SCG provided clinical data for BDR cohort.

YD performed immunochemistry and assisted with preparation of the manuscript.

AP assisted with preparation of the manuscript.

All authors read and approved the final manuscript.

Declaration of Interest

The authors have no conflict of interest to report.

Research Ethics Committee Approval

The study was approved by Manchester Brain Bank Management Committee (REC reference

19/NE/0242). Under conditions agreed with the Research Ethics Committee, The Manchester

Brain Bank can supply tissue or data to researchers, without requirement for researchers to

apply individually to the REC for approval.

16

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24

BDR ULMCHAp value

N % N %

Sex

Male 45 51.7 29 29.60.002

Female 42 48.3 69 70.4

Cognitive status

Normal 30 34.5 69 70.4<0.001

Impaired 57 65.5 29 29.6

Presence of APOE ε4 allele(s)

Absent 45 51.7 71 72.4

0.008Present 39 44.8 27 27.6

Missing 3 3.4 0 0

Table 1 – Demographics of the 185 eligible participants split by cohort (BDR – Brains for

Dementia Research cohort; UMLCHA – The University of Manchester Longitudinal Study of

Cognition in Healthy Old Age cohort).

25

BDR ULMCHA Combined cohorts

Cognitively

unimpaired

Cognitively

impaired

Cognitively

unimpaired

Cognitively

impaired

Cognitively

unimpaired

Cognitively

impaired

N % N % N % N % N % N %

Braak tau stage

0 - II 27 90.0 7 12.3 55 79.7 6 20.7 82 82.8 13 15.1

III - IV 3 10.0 19 33.3 14 20.3 17 58.6 17 17.2 36 41.9

V - VI 0 0 31 54.4 0 0 6 20.7 0 0 37 43.0

VCING

Low 25 83.3 45 78.9 56 81.2 22 75.9 81 81.8 67 77.9

Moderate 3 10.0 9 15.8 9 13.0 3 10.3 12 12.1 12 14.0

High 2 6.7 3 5.3 4 5.8 4 13.8 6 6.1 7 8.1

Table 2 – Distribution of Braak tau staging and VCING of the 185 eligible participants split by cohort and cognitive status (BDR – Brains for

Dementia Research cohort; UMLCHA – The University of Manchester Longitudinal Study of Cognition in Healthy Old Age cohort)

26

OR 95% C.I. p value

Moderate or severe occipital leptomeningeal CAA 4.379 1.008-19.021 0.049

Sex 0.429 0.092-1.996 0.281

Age at death 0.968 0.863-1.087 0.584

Presence of APOE ε4 allele(s) 0.685 0.116-4.051 0.677

CERAD score 0.547 0.144-2.080 0.376

Thal phase 1.630 0.502-5.294 0.416

LATE-NC 1.766 0.386-8.081 0.463

PART 0.966 0.037-25.481 0.984

SVD in BG 0.508 0.215-1.199 0.122

Table 3 – Regression analysis model for Braak stages III-IV. The significant difference in

moderate or severe occipital leptomeningeal CAA between cognitively normal and

cognitively impaired individuals remains after controlling for sex, age at death, presence of

APOE ε4 allele(s), CERAD score, Thal phase, PART, LATE-NC and SVD in BG.

27

28

29

30

Figure legends

Figure 1 – Example of mild (panel A) moderate (panel B) and severe (panel C) occipital

leptomeningeal CAA (Case numbers 17/32, 18/09 and 16/45 respectively)

Figure 2 – Comparisons of vascular measures (presence or absence of i) one or more large

(>10mm) cerebral infarcts; ii) moderate or severe occipital leptomeningeal CAA (Figure 1);

iii) moderate or severe occipital WM arteriosclerosis) between each Braak stage group,

irrespective of presence/absence of cognitive impairment. Panel A: Individual VCING

measures; Panel B: VCING score showing likelihood that cerebrovascular disease

contributed to cognitive impairment.

Figure 3 - Comparisons of vascular measures between cognitively unimpaired (white) and

cognitively impaired (black) members of each Braak stage group. Panel A: Presence of one

or more large (>10mm) cerebral infarcts; Panel B: Presence of moderate or severe occipital

leptomeningeal CAA; Panel C: Presence of moderate or severe occipital WM arteriosclerosis;

Panel D: VCING score showing likelihood that cerebrovascular disease contributed to

cognitive impairment.

Note - the influence of sex, age at death, presence of APOE ε4 allele(s), Thal phase, CERAD

score, presence/severity of PART pathology, presence/severity of LATE pathology and SVD

in BG did not alter the significant outcomes found for moderate or severe occipital

leptomeningeal CAA at Braak stages III-IV between cognitively impaired and cognitively

unimpaired individuals.

31

SUPPLEMENTARY TABLE 1

Case No. Cohort CERAD score Thal phase Braak tau stage Infarcts CAA Arterio VCING

Braak LB

stage

LATE-NC

stagePART SVD in

BG

DPM04/12 UMLCHA 0 0 II 0 0 1 Low 0 0-1 Definite 2DPM05/05 UMLCHA B 3 III 0 0 0 Low 0 0-1 Absent 1DPM06/03 UMLCHA A 5 IV 0 0 0 Low 0 0-1 Absent 2DPM06/08 UMLCHA B 3 IV 0 0 0 Low 0 0-1 Absent 1DPM06/11 UMLCHA C 4 IV 0 0 0 Low 0 0-1 Absent 2DPM06/18 UMLCHA C 4 IV 0 0 1 Low 0 2-3 Absent 2DPM07/07 UMLCHA 0 0 I 0 1 1 Moderate 0 0-1 Definite 2DPM07/10 UMLCHA C 3 III 0 1 1 Moderate 0 0-1 Absent 2DPM07/13 UMLCHA 0 0 0 0 0 1 Low 0 0-1 Absent 3DPM08/04 UMLCHA A 4 I 0 0 0 Low 0 0-1 Absent 2DPM08/28 UMLCHA A 3 0 1 0 1 High 0 0-1 Absent 2DPM08/29 UMLCHA A 5 II 0 1 1 Moderate 0 0-1 Absent 2DPM09/05 UMLCHA 0 0 II 0 0 0 Low 0 0-1 Definite 2DPM09/07 UMLCHA B 4 III 0 0 1 Low 0 2-3 Absent 2DPM09/13 BDR B 3 II 0 0 0 Low 0 0-1 Absent 1DPM09/14 BDR B 3 IV 0 0 1 Low 0 0-1 Absent 1DPM09/15 UMLCHA C 4 IV 0 0 0 Low 0 0-1 Absent 1DPM09/19 BDR C 3 IV 0 0 0 Low 0 0-1 Absent 1DPM09/21 UMLCHA B 3 II 0 1 1 Moderate 0 0-1 Absent 3DPM09/22 UMLCHA B 3 III 0 1 0 Low 0 0-1 Absent 2DPM09/24 UMLCHA 0 0 0 0 0 0 Low 0 0-1 Absent 1DPM09/26 UMLCHA 0 0 I 0 0 0 Low 0 0-1 Definite 1DPM09/27 BDR C 3 VI 0 1 0 Low 0 0-1 Absent 2DPM09/31 UMLCHA 0 0 I 0 0 0 Low 0 0-1 Definite 2

32

DPM09/35 BDR B 4 III 1 1 0 High 0 0-1 Absent 1DPM09/37 BDR 0 1 0 0 0 0 Low 0 0-1 Absent 1DPM10/01 BDR B 4 III 1 0 0 Moderate 0 0-1 Absent 2DPM10/02 BDR C 4 VI 0 0 0 Low 0 0-1 Absent 2DPM10/04 BDR B 3 III 0 0 1 Low 0 2-3 Absent 2DPM10/07 UMLCHA B 5 IV 1 1 1 High 0 2-3 Absent 3DPM10/08 UMLCHA B 5 III 0 1 1 Moderate 0 2-3 Absent 2DPM10/09 BDR C 5 V 0 1 0 Low 0 0-1 Absent 1DPM10/10 BDR C 3 VI 0 0 1 Low 0 0-1 Absent 2DPM10/12 BDR B 4 IV 1 1 0 High 0 0-1 Absent 1DPM10/13 BDR C 3 VI 0 1 0 Low 0 0-1 Absent 0DPM10/14 BDR B 3 III 0 1 1 Moderate 0 2-3 Absent 2DPM10/15 BDR C 5 VI 0 1 0 Low 0 0-1 Absent 1DPM10/16 UMLCHA B 3 III 1 0 1 High 0 0-1 Absent 2DPM10/18 BDR B 3 III 0 1 0 Low 0 2-3 Absent 1DPM10/20 BDR B 4 IV 0 1 1 Moderate 0 2-3 Absent 2DPM10/25 BDR A 3 III 0 1 0 Low 0 0-1 Absent 1DPM10/26 BDR 0 0 0 0 0 1 Low 0 0-1 Absent 2DPM10/27 BDR B 4 III 0 1 0 Low 0 0-1 Absent 1DPM10/30 BDR 0 0 0 0 0 0 Low 0 0-1 Absent 0DPM10/31 BDR C 3 VI 0 1 0 Low 0 2-3 Absent 1DPM10/40 UMLCHA B 3 III 0 0 0 Low 0 0-1 Absent 1DPM11/02 BDR C 5 V 0 1 0 Low 0 0-1 Absent 0DPM11/03 BDR A 4 I 0 0 0 Low 0 2-3 Absent 0DPM11/06 UMLCHA A 1 II 0 0 0 Low 0 0-1 Possible 2DPM11/07 UMLCHA 0 0 0 0 0 0 Low 0 0-1 Absent 1DPM11/15 UMLCHA 0 0 I 0 0 1 Low 0 0-1 Definite 2DPM11/20 UMLCHA B 1 II 0 0 0 Low 0 0-1 Possible 2

33

DPM11/22 UMLCHA 0 0 0 0 0 1 Low 0 0-1 Absent 2DPM11/25 UMLCHA 0 0 II 0 0 0 Low 0 0-1 Definite 0DPM11/27 UMLCHA A 1 II 0 0 0 Low 0 0-1 Possible 1DPM11/28 BDR C 5 VI 0 0 0 Low 0 0-1 Absent 0DPM11/29 UMLCHA 0 0 II 0 0 0 Low 0 0-1 Definite 1DPM12/03 BDR C 5 VI 0 0 0 Low 0 0-1 Absent 1DPM12/05 BDR C 5 VI 0 1 0 Low 0 0-1 Absent 2DPM12/09 UMLCHA A 1 I 0 0 0 Low 0 0-1 Possible 1DPM12/10 BDR B 4 III 0 0 0 Low 0 0-1 Absent 1DPM12/11 BDR 0 0 0 0 0 0 Low 0 0-1 Absent 1DPM12/16 BDR A 2 0 0 0 0 Low 0 0-1 Absent 0DPM12/17 BDR C 5 VI 0 1 0 Low 0 2-3 Absent 0DPM12/20 BDR A 3 III 0 0 0 Low 0 0-1 Absent 1DPM12/21 BDR B 5 IV 0 1 1 Moderate 0 2-3 Absent 3DPM12/22 BDR B 3 II 0 1 1 Moderate 0 0-1 Absent 3DPM12/23 UMLCHA 0 0 I 0 0 0 Low 0 0-1 Definite 1DPM12/24 BDR A 3 V 1 1 0 High 0 2-3 Absent 2DPM12/25 BDR C 3 IV 0 1 0 Low 0 0-1 Absent 0DPM12/28 UMLCHA A 3 II 0 1 0 Low 0 0-1 Absent 1DPM12/29 BDR C 5 II 0 0 0 Low 0 0-1 Absent 0DPM12/33 UMLCHA B 4 III 0 1 1 Moderate 0 0-1 Absent 2DPM12/34 UMLCHA B 1 III 0 0 0 Low 0 0-1 Possible 1DPM12/35 UMLCHA A 3 II 0 1 0 Low 0 0-1 Absent 2DPM13/10 UMLCHA B 3 V 0 0 0 Low 0 0-1 Absent 1DPM13/11 UMLCHA B 3 IV 0 1 0 Low 0 2-3 Absent 0DPM13/12 UMLCHA A 1 II 0 0 0 Low 0 0-1 Possible 1DPM13/16 UMLCHA B 5 III 0 1 0 Low 0 2-3 Absent 3DPM13/17 UMLCHA B 3 III 1 1 1 High 0 2-3 Absent 2

34

DPM13/20 BDR B 3 IV 0 0 0 Low 0 2-3 Absent 1DPM13/21 UMLCHA 0 0 II 0 0 1 Low 0 0-1 Definite 2DPM13/23 UMLCHA A 0 II 0 0 0 Low 0 0-1 Definite 2DPM13/25 BDR A 2 II 0 0 0 Low 0 0-1 Possible 1DPM13/30 BDR C 3 IV 0 1 0 Low 0 0-1 Absent 0DPM13/31 UMLCHA 0 0 II 0 0 0 Low 0 0-1 Definite 2DPM13/32 UMLCHA A 1 0 0 0 1 Low 0 0-1 Absent 0DPM13/33 BDR C 3 V 0 1 0 Low 0 0-1 Absent 0DPM13/35 UMLCHA 0 0 I 1 0 0 Moderate 0 0-1 Definite 0DPM13/36 UMLCHA A 3 II 0 1 0 Low 0 0-1 Absent 0DPM13/40 BDR A 3 III 0 0 1 Low 0 2-3 Absent 0DPM13/44 BDR B 5 V 0 1 1 Moderate 0 0-1 Absent 2DPM13/45 BDR C 5 V 0 0 0 Low 0 0-1 Absent 0DPM14/01 UMLCHA B 4 IV 0 0 0 Low 0 0-1 Absent 0DPM14/03 BDR C 5 VI 0 0 0 Low 0 0-1 Absent 0DPM14/04 UMLCHA A 1 0 0 0 0 Low 0 0-1 Absent 1DPM14/06 UMLCHA B 1 II 0 1 0 Low 0 0-1 Possible 0DPM14/08 BDR A 2 0 0 0 1 Low 0 0-1 Absent 2DPM14/09 BDR A 2 I 0 0 1 Low 0 0-1 Possible 2DPM14/11 UMLCHA 0 0 I 0 0 0 Low 0 0-1 Definite 2DPM14/14 UMLCHA B 3 II 0 1 0 Low 0 0-1 Absent 0DPM14/16 UMLCHA A 1 0 0 0 0 Low 0 0-1 Absent 0DPM14/18 BDR C 3 III 0 0 1 Low 0 0-1 Absent 2DPM14/20 UMLCHA 0 0 0 0 0 0 Low 0 0-1 Absent 0DPM14/22 BDR C 5 VI 0 1 0 Low 0 0-1 Absent 2DPM14/27 BDR A 1 I 0 0 0 Low 0 0-1 Possible 0DPM14/28 BDR C 3 VI 0 0 0 Low 0 0-1 Absent 0DPM14/29 UMLCHA B 1 II 0 0 0 Low 0 0-1 Possible 0

35

DPM14/34 BDR B 3 II 0 0 0 Low 0 0-1 Absent 2DPM14/35 BDR B 3 III 0 0 0 Low 0 0-1 Absent 2DPM14/42 UMLCHA B 3 III 0 0 0 Low 0 2-3 Absent 0DPM14/46 UMLCHA 0 0 0 0 0 0 Low 0 0-1 Absent 1DPM14/47 BDR A 2 II 0 1 0 Low 0 0-1 Possible 1DPM15/01 UMLCHA A 1 I 0 0 1 Low 0 0-1 Possible 1DPM15/05 UMLCHA A 1 I 0 1 0 Low 0 0-1 Possible 1DPM15/07 BDR C 5 VI 0 0 0 Low 0 0-1 Absent 0DPM15/11 UMLCHA C 5 VI 0 1 1 Moderate 0 2-3 Absent 3DPM15/14 UMLCHA B 3 III 0 1 1 Moderate 0 0-1 Absent 2DPM15/15 UMLCHA 0 0 II 1 0 0 Moderate 0 0-1 Definite 2DPM15/19 UMLCHA B 2 III 1 0 1 High 0 0-1 Possible 2DPM15/20 BDR C 5 VI 0 1 1 Moderate 0 0-1 Absent 1DPM15/21 BDR C 5 VI 0 1 1 Moderate 0 0-1 Absent 2DPM15/22 BDR A 2 I 0 0 1 Low 0 2-3 Possible 2DPM15/26 UMLCHA A 3 0 0 0 0 Low 0 0-1 Absent 1DPM15/28 UMLCHA 0 0 II 1 0 0 Moderate 0 0-1 Definite 1DPM15/29 BDR C 5 V 0 0 0 Low 0 0-1 Absent 1DPM15/30 UMLCHA A 2 II 0 0 0 Low 0 0-1 Possible 0DPM15/31 UMLCHA A 3 I 0 0 0 Low 0 0-1 Absent 1DPM15/42 UMLCHA B 5 III 0 1 0 Low 0 0-1 Absent 0DPM15/48 BDR C 5 VI 0 0 1 Low 0 2-3 Absent 0DPM16/01 UMLCHA B 4 III 0 0 0 Low 0 2-3 Absent 1DPM16/02 BDR A 1 II 1 0 1 High 0 0-1 Possible 3DPM16/03 UMLCHA C 3 V 0 1 0 Low 0 0-1 Absent 0DPM16/06 BDR 0 0 0 0 0 0 Low 0 0-1 Absent 0DPM16/07 BDR 0 0 I 1 0 0 Moderate 0 0-1 Definite 0DPM16/08 BDR B 3 IV 0 1 1 Moderate 0 0-1 Absent 3

36

DPM16/10 BDR C 5 VI 0 1 0 Low 0 0-1 Absent 0DPM16/11 BDR 0 0 I 1 0 0 Moderate 0 0-1 Definite 2DPM16/12 UMLCHA 0 0 II 0 0 0 Low 0 0-1 Definite 2DPM16/13 UMLCHA C 5 V 0 0 0 Low 0 0-1 Absent 2DPM16/14 BDR C 4 V 0 0 0 Low 0 2-3 Absent 0DPM16/15 UMLCHA B 2 II 1 1 1 High 0 0-1 Possible 2DPM16/16 BDR C 3 V 0 1 0 Low 0 2-3 Absent 0DPM16/18 UMLCHA B 3 I 0 0 1 Low 0 0-1 Absent 2DPM16/19 UMLCHA B 2 II 1 0 1 High 0 0-1 Possible 3DPM16/23 UMLCHA 0 0 I 0 0 0 Low 0 0-1 Definite 0DPM16/24 UMLCHA 0 0 I 0 0 0 Low 0 0-1 Definite 0DPM16/29 BDR A 2 0 0 0 0 Low 0 0-1 Absent 0DPM16/31 BDR A 2 I 0 0 0 Low 0 0-1 Possible 1DPM16/35 BDR B 2 II 0 0 0 Low 0 0-1 Possible 2DPM16/37 UMLCHA B 2 III 0 1 0 Low 0 2-3 Possible 0DPM16/38 BDR A 3 I 0 0 0 Low 0 0-1 Absent 1DPM16/41 UMLCHA A 2 I 0 1 0 Low 0 0-1 Possible 0DPM16/43 UMLCHA B 4 III 0 0 0 Low 0 0-1 Absent 0DPM16/44 BDR A 3 II 0 1 0 Low 0 0-1 Absent 0DPM16/45 UMLCHA B 5 III 0 1 0 Low 0 2-3 Absent 0DPM17/03 BDR 0 0 I 0 0 0 Low 0 0-1 Definite 2DPM17/04 UMLCHA 0 0 I 0 0 0 Low 0 0-1 Definite 0DPM17/07 BDR C 3 V 0 0 0 Low 0 0-1 Absent 0DPM17/09 UMLCHA 0 0 I 0 0 0 Low 0 0-1 Definite 0DPM17/17 BDR A 3 I 0 1 0 Low 0 0-1 Absent 1DPM17/22 UMLCHA A 2 II 0 0 0 Low 0 0-1 Possible 1DPM17/23 BDR A 3 II 0 0 0 Low 0 0-1 Absent 1DPM17/26 BDR A 1 I 0 0 0 Low 0 0-1 Possible 1

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DPM17/27 BDR B 3 IV 0 1 1 Moderate 0 0-1 Absent 2DPM17/29 UMLCHA A 2 II 0 0 0 Low 0 0-1 Possible 1DPM17/31 BDR A 3 II 1 1 1 High 0 0-1 Absent 2DPM17/32 UMLCHA B 3 IV 0 0 0 Low 0 0-1 Absent 1DPM17/36 BDR A 3 I 0 0 0 Low 0 0-1 Absent 1DPM17/37 BDR C 3 V 0 0 0 Low 0 0-1 Absent 1DPM17/38 UMLCHA A 1 II 0 0 0 Low 0 0-1 Possible 1DPM18/02 BDR 0 0 II 0 0 1 Low 0 0-1 Definite 3DPM18/03 UMLCHA 0 0 0 0 0 0 Low 0 0-1 Absent 1DPM18/05 BDR 0 0 I 0 0 0 Low 0 0-1 Definite 1DPM18/07 BDR 0 1 0 0 0 0 Low 0 0-1 Absent 0DPM18/09 UMLCHA B 3 IV 0 1 1 Moderate 0 0-1 Absent 2DPM18/11 UMLCHA A 1 I 0 0 0 Low 0 0-1 Possible 3DPM18/12 BDR C 5 V 0 0 0 Low 0 0-1 Absent 3DPM18/18 UMLCHA A 2 III 0 0 0 Low 0 0-1 Possible 0DPM18/21 BDR C 3 VI 0 0 1 Low 0 0-1 Absent 2DPM18/32 UMLCHA B 2 II 0 0 1 Low 0 0-1 Possible 3DPM18/38 UMLCHA A 3 IV 1 1 1 High 0 0-1 Absent 3DPM19/09 UMLCHA 0 1 II 0 0 1 Low 0 0-1 Absent 3DPM19/12 UMLCHA C 3 VI 0 0 0 Low 0 2-3 Absent 1DPM19/20 UMLCHA C 3 VI 0 0 1 Low 0 0-1 Absent 2

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